Process of treating aluminum skimmings, screenings, &amp;c.



mvrrnn s'rairns ra'rnner orrron.

JAMES WRIGHT LAWRIE, or AURUBA, ILLINOIS, ASSIGNOB T0 WILLIAM F. JOBBINS, INCORPORATED, or AURORA, ILLINoIs, A CQRPORATION or ILLINOIS.

PROCESS OF TREATING ALUMINUM SKIMMINGS, SCREENIN GS, &c.

No Drawing.

To all whom it may concern:

Be it known that 1, JAMES WRIGHT LAW- RIE, a citizen of the United States, residing at Aurora, in the county of Kane and State of Illinois, have invented a new and useful Improvement in Process of Treating Alu-' minum Skimmings, Screenings, Dress, Slags, or Analogous Aluminous Materials, of which the following is a specification.

My invention relates to a process of treating aluminum skimmings, screenings, dross, slags or analogous aluminous materials, for

the purpose of producing therefrom certain valuable and usefulproducts.

In carrying outmy invention the skimmings are first separated by suitable means, such as screens and the like, from the larger particles and pieces of free aluminum or its alloysoccurring with them. The iron or its 'water'. This residue may beutilized for the production of aluminum compounds by treating with a solvent of aluminum either acid or alkaline. But the presence (in more than small quantities) of free metal and of carbids and nitrids in the material is very objectionable, especially when the material 1 is treated directly with acids for the proother hydrocarbons.

'duction of aluminum salts.

when acted upon by acld are decomposed,

he carbids yielding products in part gaseous, which gases consist chiefly of methane and possibly The free metal also reacts with acids. liberating hydrogen. The evolution of. these gases causes extensive foaming, thus necessitating either very slow mixing of the material with the acid or considerable dilution of the acid, both of which alternatives are objectionable features insuch a process. Likewise,- T have found that explosions sometimes occur when the material isdirectly treated with acid, due probably to the presence of hydrogen and the. high temperatures produced. In the acid treatment the presence of free metal has the additional disadvantage that it interferes with the most economical recovery of the copper contained in the material in the form of easily soluble copper compounds,

Specification 01 Letters Patent.

.nitrids in the material.

Patented Apr. 9, 1918.

Application filed August 1, 1914. Serial No. 854,471.

for the free aluminum acts upon the dissolved copper, precipitatmg the latter and thus mixing it in with the residue from which it is less easily extracted than from the solution. These difliculties are encountered also when the material is to be treated with alkalis for the production of solutions of alkali-metal aluminates, but are there not so great. Another difficulty to be avoided if the most economical utilization of this material is to be accomplished, in the acid treatment. is occasioned by the presence of WVhen these nitrids are acted upon by acids, salts of ammonia are produced. -These salts will appear in the final aluminum salt, and will therefore contaminate the latter. Further, more acid is required to produce the ammonium salt, and consequently the presence of nitrids results in the necessity of using an excess of acid, which adds nothing to the value of the final product and is therefore wasted. Finally, in the direct treatment of the residue with acid the ammonia is not regained in commercially available form. By my invention which I describe below the material is first suitably prepared, at very small cost, by removing to a large extent the carbids, nitrids and free metal, and then treating the thus prepared material for the recovery ofits aluminous and other contents.

In my process the material, from which the larger particles and pieces of any free metal or magnetic iron or its compounds have been removed, is boiled with water under pressure. I have found that while aluminum carbid is only exceedingly lowly decomposed by water boiling at atmospheric pressure, this decomposition is greatly hastened at the higher temperatures by water under increased pressure. Even under these conditions the earbids may not be completely decomposed, but the amount left after the treatment is so small as to cause no difficulty. A similar statement may be made in regard to the free metal' This is oxidized very slowly by water at 100 degrees (l, but more rapidly at higher temperatures, and while likewise not completely removed is oxidized so far that it no longer interferes greatly with the acid process. The nitrids are apparently decomposed far more readily than the carbide or the metal, and therefore a temperature high enough to produce any considerable decomposition of "25' desirable. from the liquid, may betreated a 13mm sulfate need not e imi e t e 'p er limiu'aryftreatmehtifwith diluted:'acidfcan be omittedi The aluminum sulfate; liquor re-.

' t f suiting from the treatment Withstroug acid l henpurified from copper by precipitating thelatt'er'either-as-metalli copper or as'jcop- 5'; j :ipefjsulfidi jThis may done bytreatin v 'i" thesolutionjwitha metal trimm d higher I electrolytic Solution pressure' thari copper,

.1ereferably. "aluniiiiurn' dust separated frni 1,, o [the,origmalkimmings, or-byfsubjeoting the 1m 'suflieientftodecoxnposethe riitrids. I find V that boiling under pressure o, 80' pounds V jiforthreehours under suitableconditionsac- 5 omp i hsiv-th s nurw sflhSfM bflW An "important condition for thebest results from t 7 the proc ss is that ihehfixtureofthe mate;

rialf and Water is continuously agitated 5 throughout the process lofboil-ing, h ir this {10 is not done the solid settlesin the as a Y cake and does not enter completely mtore'ac- The ammonia, evolved in this steprrna T parated from'the other gases andco -V:

'lectfed and the remaining gases utilized.

The'resulting residue maythen be separated from the. quid, which step hasthe advantage ofremoving from the material" anysoluble :substances which may have been originally contained, but this step is not ,itreatments' above described may be treated "for therecovery'of compounds of aluminum, of copper or its compounds and of other bywayis; :Thusthe so. id residue, sep'aratedif with a solution 7 of alkaline. caustic: at ele- '7 :rated itemgerature forming an" illuminate T soimien w ch. may -be-utilized for theproan, auction or hydrate of swine; Them:

J n-ea: method of. treating the residu -se- {suiting from the hoilingfirithi i'ater', h0w-" m isto' use {arr acid for theidirect prod1ico o V v I pounds frorn alum num ski -tugs which tron "ofaluminum salts, preferablylsulfuric 4 lutedf Sulfuric acid for-the removalfof the pm ofthe iron,;which treatment dis.-

{solves only arelatively small amouiit of-the V aluminous contenhthe amount of acid being 40' so'chosenthat only small-amountsofahimh num-are dissolved;*Theundissoliedportion I separated from-the liquid land istreated with conceutrated"acid,,c thus forming an aluminum sulfate 7 fsolutio'u, j" usually eon- .terialfmay' not a in imm eri l," h b "Shown always "necessary. The residue from the i productsw'lhismai be-done in onefof two.

,solvir 'iglthelresidueinsuch acid;

acid; Themateriahis treated first with di with anacid inwhich said s soluble andthen dissolving there's no o Vfir's t'preparing the said material by boiling taminated with copper and small amounts fof The cooper of the ori fuel raw 'ma llbeiound in 't 0 solution if there: is much free aluminum' orits alloys f V Vwhieh said} solids are solubleiorthe pro above; I'f-the amount of'iro'n inj'the aiuinu 'cipitatingthe-copper from the latter, and

: lu'tion to obtain fol-ma t preparing the 'sai-danilaterial by boiling the" sameyvith Water under pressurejor the pur- -pose ofjde'eomposingnitrids and carbide and 7 ofoxidi'zing the remaining free metal, then f yhigh to liberatehydrogen or-oxygen. 17; I t'heicoppei'jmay beprecipitated as copper u y theme of hydrogen sulfid or other V sulfids.v jThe solution is S parated treatment with acid rnay be made 'continu bus, or'*thegases other-than the; 'af'mmmiie may be utilized, 0r anyotherchanges may '75 be made which may suggest themselve to those skilled in'the art. a F *Iclaimr M .7 H 1. The process oifoi'mingr liirniuum compounds from; aluminum" skimmings" which 7 consistsin treati gthe skimmings to remove ingredientscapable of evolvin gases when the lskirnmings ere treated with a solvent and then dissolving the residue. t

2; The process of forming aluminum compounds which consists in treating aluminum skimmings to remove therefrom ingredients 5 capable' oi;evolving; see when the skim min'gs are treated-with anaeid in which 'saidtskimniings are soluble and hen e process oi forrnin aluminum compounds' from aluminum shunning: which "consists; in the skimmings in Water to rerhove'ing're ents'ca'pabl'eof evolving gases in thefisubsequent'treatment and than dissolving theresiduer 1.5 4. The processo'i ing aluminum comconsists in: boilingtthe 's'kiinmings in water ing gases-when thew'skimrninis are treated 'immin s are sueh'acidym '7 I 5. The "method; of] treatin aluminum ski'rhmi'ngs, screenings, drossfs age or mate-.5

gous alumi'nousmaterials, which consists. m-

the samewith-water under" pressure for the purpose of decomposing nitridsand' oarbids and-'ofoxidizing rema ning free'metal, then.

evaporating the" purified al min m salt 50- or aluminum salt in solid 6 Therflfethodgof treating aluminum" skimmings, screenings, dross,-'.sl8gs or'analo gous alum-inous materials from which any larger pieces of free aluminum or its: alloys have been removed, which consists in first treating'theresidual solids: with dilute acid I00 itoremove the ingredients capable of evohnot the solution from the solids, treating the solids with strong acid in Which said solids are soluble, and evaporating the solution to obtain the aluminum salt in solid form.

7 The method of treating aluminum skimmings, screenings, dross, slags or'analogous aluminous materials from which any larger pieces oi free aluminum or its alloys have been removed, which consists in first preparingthe said material by boiling the same With Water under pressure for the purpose of decomposing nitrids and carbids and of oxidizing the remaining free metal, then treating the residual solids With'dilute acid to remove the bulk of the iron, separating the solution from the solids, treating the solids With strong acid in Which said solids are soluble for the production of an aluminum salt solution, precipitating the copper from the latter, and evaporating the purified aluminum salt solution to obtain the salt in solid form.

8. The method of treating aluminum skimniings, screenings, dross, slags or analogous aluminous materials from Which any larger pieces of free aluminum or its alloys have been removed, which consists in first preparing the said material by boiling the same With Water under pressure and simultaneously agitating the mixture for the purpose of decomposing nitrids and carbids and of oxidizing the remaining free metal, then treating the residual solids With dilute acid to remove the bulk of the iron, separating the solution from the solids, treating the solids with strong acid in which said solids are soluble for the production of an aluminum salt solution, precipitating the copper from the latter, and evaporating the purified aluminum salt solution to obtain the salt in solid form.

JAMES WRIGHT LAWRIE.

Witnesses PEARL GRISCH, WALTER BRAUN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. 0. 

